mere2.cpp: In function 'int main()': mere2.cpp:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result mere2.cpp:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result mere2.cpp:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result mere2.cpp:21: warning: 'x' may be used uninitialized in this function mere2.cpp:21: warning: 'y' may be used uninitialized in this function mere2.cpp:21: warning: 'z' may be used uninitialized in this function